Titanium face plate for cellular phone with crystalline grain texture

ABSTRACT

Disclosed herein is a scratch-resistant article for covering an object, such as a cellular phone, wherein the article comprises titanium metal or titanium alloy with grain size greater than 0.030 inch. Also disclosed is a method of producing such articles comprising thermally treating titanium in vacuum at a minimum temperature of 1900° F. for at least 5 minutes.

This application claims the benefit of domestic priority to U.S. Provisional Patent Application No. 60/661,504, filed Mar. 15, 2005, which is incorporated herein by reference in its entirety.

The present disclosure is related to a titanium-containing article, such as a face plate for a cellular phone, that has been thermally treated to produce a pattern of crystalline grains upon the surface. In addition to providing a desirable decorative surface, the article provides a surface that is more wear resistant and that conceals scratches, better than traditional plastic surfaces, such as those used for cellular phone face plates. The present disclosure is also related to a method for making such articles.

Hand-held telecommunication devices, such as cellular telephones or other wireless communication devices, typically have a smooth plastic molded exterior or “face-plate”. These plastic face plates not only give a cheapen appearance to an otherwise sophisticated device, but can be slippery to grip and are prone to becoming scratched or chipped. In addition, there is a fear that exposure to cellular telephone radio frequency (transmitting and capturing electromagnetic waves in the form of microwave and electromagnetic radiation, with a typical frequency of between 900 MHz and 1,800 MH), can lead to health problems, such as promoting alterations in the cerebral electrical field, in cellular growth rate (cancer), in enzymatic activity and in the DNA genes.

Therefore, there is a need to replace traditional plastic face plates of cellular phones with a more durable, attractive material, that may have the additional benefit of mitigating the radiation that reaches the user from the cellular telephone. One material finding increasing popularity in consumer applications that may achieve the foregoing benefits is titanium.

Titanium and its alloys microstructually exist in two phases: the alpha phase, which has a close packed hexagonal structure, and the beta phase, which has a body centered cubic structure. By exposing titanium and its alloys to various thermal processes, it is possible to fabricate a product having either one or both of these phases. In addition, by manipulating the thermal processes, for example, changing the temperatures and times at which the titanium material is heated, it is possible to produce a final product having a combination of desired properties associated with tailored grain sizes. For example, by increasing the thermal cycle times and temperatures, it is possible to produce a titanium material having large grains that can be formed into a scratch-resistant titanium sheet with an attractive sparkled texture.

The resulting sheet can then be fabricated into a variety of titanium components, including watch cases, computer containers and telephone components such as cell phone bodies. The attractive “bright peckled” titanium can be used as processed or can be further anodized by conventional technology to produce a variety of colors while still retaining the speckled titanium surface.

SUMMARY

Disclosed herein is an article comprising a titanium or titanium alloy that has been thermally treated to produce a pattern of grains upon the surface for decorative purposes and for achieving a wear resistant surface. In one embodiment, the article may be a face plate for a cellular phone. In other embodiments, the article may be used in titanium or titanium alloy components, such as computer cases or the coverings of hand-held electronic devices.

Also disclosed herein is a process for producing such articles. For example, the article, which may comprise a cellular phone face plate, may be produced by stamping of commercially pure (CP) titanium, which is subsequently heated in vacuum at a temperature sufficient to induce grain growth. The resulting surface pattern is highly decorative, more wear resistant and will conceal scratches. The process may further comprise a surface treatment to produce color, including commercial anodization or additional thermal processes.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, and together with the description serve to explain the principles of the invention.

FIG. 1 illustrates a titanium cellular phone face plate that has been thermally treated to produce the decorative grain structure of the titanium.

FIG. 2 illustrates titanium cellular phone face plates that have been subjected to initial wear tests.

DESCRIPTION OF EMBODIMENTS

Disclosed herein is an article comprising a titanium face plate for a cellular phone that has been thermally treated to produce a pattern of grains upon the surface for decorative purposes. The size of the grains on the face plate may range from 0.0625 inch to 1.0 inch, depending upon the thermal treatment parameters used and the desired effect. After the thermal treatment to induce the grain growth, the color of the grains may also be affected by either anodization or thermal treatment in a reactive atmosphere such as nitrogen or oxygen. The structure of the grains is generally equiaxed.

Titanium is often used in applications such as housings on consumer products because of its high specific strength and stiffness, and because of its general commercial appeal. Commercially pure (CP) titanium is often used for these applications because its high ductility allows for extreme deformation processes such as drawing. However, CP titanium is less wear-resistant than alloyed titanium, and is subject to scratching. The material with crystalline grain texture described herein exhibits improved wear resistance. Furthermore, scratches that do occur are obscured by the patterned surface.

In one embodiment, the external housing mitigates radiation transmitted by the underlying article. For example, when formed into a cellular phone cover, the housing may reduce the radiation (typically microwave and electromagnetic radiation with a typical frequency of between 900 MHz and 1,800 MH) that is transmitted to a body in the vicinity of the cellular phone, such as the head and/or hand, of the person using the cellular phone.

Also disclosed herein is the method used to achieve the crystalline, decorative surface on the titanium cellular phone face plate. This method comprises heating the formed articles in a vacuum atmosphere at a temperature sufficient to induce grain growth in the titanium or titanium alloy. For example, in one embodiment, cellular phone face plates stamped from CP titanium were heated under vacuum to 2250° F. for 2 hours. The resulting surface finish consisted of equiaxed grains approximately 0.125 inch in size.

Other than where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches.

Notwithstanding the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the embodiments are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in its respective testing measurement. 

1. A scratch-resistant article for covering an object, said article comprising titanium metal or titanium alloy with grain size greater than 0.030 inch.
 2. The scratch-resistant article of claim 1, which is an external housing for covering a cellular phone.
 3. The scratch-resistant article of claim 2, wherein said external housing mitigates radiation transmitted by the cell phone.
 4. A method of producing a titanium containing article with grain size greater than 0.030 inch composed of thermally treating titanium in vacuum at a minimum temperature of 1900° F. for at least 5 minutes.
 5. The method of claim 4, wherein said thermally treating comprises heating at a temperature above the beta transition temperature for the titanium and subsequently cooling through this transition temperature to the alpha or alpha/beta range.
 6. The method of claim 4, further comprising at least one additional process chosen from anodizing or further thermal treatment for a time sufficient to change the color of the vacuum treated article.
 7. The method of claim 4, wherein said thermally treating comprises heating under vacuum to 2250° F. for 2 hours.
 8. The method of claim 4, wherein the resulting article comprises equiaxed grains of approximately 0.125 inch in diameter. 